The use of serological tests for the detection of syphilis and other treponemal diseases has become more and more commonly practiced in recent years. These tests are usually based on an agglutination reaction and are conducted in clinics and doctors' offices preparatory to a more extensive diagnosis of the patient.
The most commonly practiced test constitutes the use of a finely divided solid such as charcoal in conjunction with a card having a surface color contrasting to that of the solid material, see U.S. Pat. No. 3,074,853. In practice, the test utilizes a common antigen liquid which is buffered and to which is added the charcoal. A drop of the resultant antigen solution-charcoal suspension is then placed on a test card in admixture with one drop of serum. The card is then shaken and the results are visually interpreted. A further syphilis testing method has been reported by Lockyer, Brit. Journal Vener. Dis., Vol. 46, pages 290-294, 1970. This test entails the use of a scarlet red powder coupled with a Kahn antigen. Additional diagnostic reagents have recently been patented, see U.S. Pat. Nos. 3,564,089 and 3,600,494.
The known test methods, while resulting in adequate syphilis detection in most cases, are by no means perfect and each possesses its own difficulties. The charcoal test, for example, is very difficult to interpret due to the tendency of the positive and negative results to be similar in many instances. Where a definitely positive test is encountered, no difficulty arises, however, in cases where the results are in doubt, further, more extensive tests must be conducted before a definite conclusion can be drawn. The Lockyer test results in the production of a pink flocculated material but this material is very difficult to detect since the particles are very minute. Being pink, the color is not as easily detected as with the charcoal test or that of my novel invention. It has additionally been well recognized that other commonly used tests have been known to give completely erroneous results in 2.0% of the tests run and false positive results in 20% of the test cases.